ADE7758 Analog Devices, ADE7758 Datasheet - Page 47

• Manufacturer Part Number: ADE7758
• Description: Poly Phase Multifunction Energy Metering IC with Per Phase Information
• Manufacturer: Analog Devices

Example—Offset Calibration of Phase a Using Pulse Output
For this example, I
V, I
1, Frequency = 50 Hz, and CLKIN = 10 MHz.
With I
meter shows 0.009773 Hz on the APCF pulse output and
0.009773 Hz on the VARCF pulse output. This is equivalent to
0.24% for the watt measurement and 0.24% for the VAR
measurement. Using Equations 38 through 41, the values 0xFFB
and 0xFFA should be written to AWATTOS (0x39) and VAROS
(0x3C), respectively.
For AWATTOS:
For AVAROS:
Calibration Using Line Accumulation
Line cycle accumulation mode configures the nine energy
registers such that the amount of energy accumulated over an
integer number of half line cycles appears in the registers after
the LINECYC interrupt. The benefit of using this mode is that
the sinusoidal component of the active energy is eliminated.
Figure 80 shows a flow chart of how to calibrate the ADE7758
using the line accumulation mode. Calibration of all phases and
energies can be done simultaneously using this mode to save
time during calibration.
FULLSCALE
Q
Q
AWATTOS
AVAROS
TEST
=
=
, V
10
10
= 130 A, MC = 3200 impulses/kWh, Power Factor =
4
4
E
E
NOM
6
6
=
×
×
, and unity power factor, the example ADE7758
–
2
=
2
TEST
1
(
1
24
25
. 0
–
(
0024
×
×
. 0
= 50 mA, V
0024
1
4
2083
202
4
=
×
. 0
. 0
×
×
00975
0186
. 0
1
4
00975
NOM
=
)
. 0
×
= 220 V, V
014
)
. 0
×
2
014
. 0
4
0186
2
4
×
227
FULLSCALE
1
×
227
=
1
–
=
6
= 500
–
4
Rev. A | Page 47 of 68
5 .
Gain Calibration Using Line Accumulation
Gain calibration is used for meter-to-meter gain adjustment,
APCF or VARCF output rate calibration, and determining the
Wh/LSB, VARh/LSB, and VAh/LSB constant.
Step 0: Before performing the gain calibration, the
CFNUM/CFDEN (0x45/0x46) and VARCFNUM/VARCFDEN
(0x47/0x48) values can be set to achieve the correct
impulses/kWh, impulses/kVAh, or impulses/kVARh using the
same method outlined in Step 4 in the Gain Calibration Using
Pulse Output section. The calibration of xWG/xVARG/xVAG
(0x2A through 0x32) is done with the line accumulation mode.
Figure 81 shows the steps involved in calibrating the gain
registers using the line accumulation mode.
Figure 80. Calibration Using Line Accumulation
OFFSET @ I
CAL VRMS OFFSET
CAL VAR GAIN ALL
CALIBRATE PHASE
CAL WATT AND VA
CAL IRMS OFFSET
GAIN ALL PHASES
PHASES @ PF = 0
CALIBRATE ALL
CALIBRATE ALL
OFFSETS @ I
PHASES WATT
ALL PHASES
PHASES VAR
AND PF = 0
@ PF = 0.5
@ PF = 1
START
PF = 1
END
MIN
MIN
AND
ADE7758